Northeast Region Certified Crop Adviser (NRCCA) Study Resources

In This Section

• PO 10 Weed life cycles
• PO 11 Weed survival mechanisms
• PO 12 Common weed identification
• PO 13 Dichotomous key
• PO 14 Timing of control
• PO 15 Mechanical weed control
• PO 16 Cultural weed control
• PO 17 Biological weed control
• PO 18 Chemical weed control
• PO 19 Herbicide site of action
• PO 20 Environmental affects herbicides performance
• PO 21 Problems associated with herbicide use

Competency Area 2: Weed Management

PO 13. Be familiar with use of a dichotomous key to identify weeds.

Keys for identifying weeds are outlines of alternative statements or choices about plant parts or appearance. From each pair of statements, you choose the one that applies to the plant you are identifying. After you have made that choice, you choose from the next pair subordinate to the first, and so on, until you come to the name of the plant. (From “Weeds of the North Central States”, North Central Regional Research Publication No. 281, Bulletin 772, University of Illinois at Urbana-Champaign). Simple keys can be found in many plant identification publications.